Hear me out on this

[AFTT47]

It takes literally billions of years from solar system formation to evolution of complex life. Even if intelligent life is very common, any such life in our vicinity is extremely unlikely to be anywhere close to the same level of development as us. Even within a million years would be lucky. So intelligent aliens are extremely likely to be either cavemen or more likely, advanced to the point where they would seem like gods. Two civilizations at the same level would likely be separated by so much distance, they would never meet - never mind contend over a planet.

The whole idea of needing planets to colonize is a bit antiquated, imo. The physicist Gerrard K. O'Neil did a study on this in the 70s and concluded that planets are not well-suited as bases for technological civilizations. Orbital space colonies can be built with any simulated gravity you want, no gravity well to escape from and limitless solar power. Asteroids are more likely to be valued by a space-going civilizations because they contain all the resources needed for building such colonies. And systems with asteroids are probably not in short supply. Our own solar system contains the resources needed to build huge numbers of space colonies with a cumulative living area thousands of times greater than Earth''s surface.